pic) Yeon, Gaesomun
(Prime Minister); Commander-in-Chief. He became
a high-level politician at 15 in succession of
his father. In 642 A.D, he constructed Chol-li-jang-sung
(1,000-ri (400km) Great Wall). In the same year,
he seized a political power as a Dae-mak-ri-ji
(Prime Minister) with King Bojang by overthrowing
King Youngryu and his 180 fellow politicians who
were opposed to him. In 645, Yeon, Gaesomun defeated
Tang's hundreds of thousand troops sent by King
Taizong several times.
The death of Yeon, Gaesomun brought Koguryo the
fatal, internal disruption over the succession
of political and military power, and this unfortunately
led Koguryo be on the road to collapse.